1. Field of the Invention
This invention relates to a recording and reproducing apparatus, and more particularly to an apparatus which is arranged to record table-of-contents information to be used in making a search for the contents of a record on a recording medium which is used for recording and reproducing main information.
2. Description of the Related Art
Some of known recording and reproducing apparatuses, such as a digital audio tape recorder (hereinafter referred to as DAT) have been arranged to write information about a table of contents of a record such as music numbers in the leader part of a magnetic tape which is employed as a recording medium and the table-of-contents information is used in making a search for the contents of a record. In the case of a video tape recorder (hereinafter referred to as VTR), information about a table of contents which are video programs is arranged to be recorded and reproduced for the same purpose.
If the DAT is of a rotary head type (hereinafter referred to as R-DAT), it is conceivable to write the above-stated table-of-contents information in a sub-code area in a known manner. The details of the sub-code are as described, for example, in an article entitled "Sub-code Format and Use of It" appeared in the Nov., 1987 issue of "JAS Journal". FIGS. 1 and 2 of the accompanying drawings are excerpted from this article.
FIG. 1 shows the track format of the R-DAT and FIG. 2 a recording data format.
As shown in FIG. 1, in the case of the R-DAT, tracks of two different kinds, including minus azimuth tracks and plus azimuth tracks, are alternately recorded in the traveling direction of the tape. Each of these tracks, roughly speaking, consists of sub-data areas 1 and 2; ATF areas 1 and 2 in which pilot signals for automatic track finding (hereinafter referred to as ATF) are recorded for a tracking servo; and a main data area. The sub-data areas are provided for recording data to be used in making a high speed search for a music number, a time code, a program number, etc. These sub-data areas are arranged to permit the addition by after-recording of a table of contents of music items or other program number, etc. The main data area is provided for recording an audio signal which is pulse-code-modulated (hereinafter referred to as PCM).
The details of the sub-code recording format for the sub-data areas are as shown in FIG. 2. Each of the sub-data areas 1 and 2 consists of eight blocks. The sub-data areas thus include a total of 16 blocks. Each sub-data area includes a block synchronizing data area SYNC; a sub-ID area which is provided for an identification code; a sub-ID parity area which is provided for sub-ID parity; and a sub-data part which follows the sub-ID parity area is provided for allowing such data as a time code, date, etc., to be written therein.
A main ID code has an 8-block completing type format. Even-number blocks are provided mainly for identifying the properties (attributes) of PCM audio data, such as a sampling frequency, a channel number, the number of quantizing bits, a track pitch, etc. Odd-number blocks are provided for recording search codes, such as codes for a program number, a time code, etc.
Generally, the conventional recording and reproducing apparatus is arranged to write the table-of-contents information in the leader part of the magnetic tape. In reproducing the table-of-contents information or in making an addition to the table-of-contents information or in rewriting it, therefore, the magnetic tape must be rewound back to its leader position. This has presented a problem in terms of operability. While this presents no problem in cases where a magnetic disc is employed as the recording medium, this has necessitated much time and labor in the case of the magnetic tape.